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Anyone knows difference between CFW and CFWN eyepieces?
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JohnyM



Joined: 24 Dec 2013
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PostPosted: Mon Jun 25, 2018 10:55 am    Post subject: Anyone knows difference between CFW and CFWN eyepieces? Reply with quote

Like in topic. Seems that CFW eyepieces were produced along CF objectives and CFWN along CFN objectives. AFAIK all corrections are made in the objective for both CF and CFN so they should be optically similar if not identical. Why nikon bothered to change them then? Yellow inscriptions are ugly that much is true, but is there any other reason?

Im gonna be able to test it quite soon, as i have CFUW 10x/25 and CFUWN 10x/26.5 and UW head for microphot is on the way.
Problem i expect to encounter is that biological CF N objectives were stated to work with FN25 and FN26.5 was made for metallurgical EPI objectives - so there might be some vignetting on CFUWN. I know that bio CF N's do have quite big image circle, but microscope itself can induce vignetting like it does in photoport (i had to made some quite extensive modifications in microphot, to be able to cover APS-C with no vignetting).
On the other hand i use CF N objectives, and i wonder if i need to hunt for 3rd set of UW eyepieces (CFUWN FN25).
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Pau
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PostPosted: Mon Jun 25, 2018 2:28 pm    Post subject: Reply with quote

I don't know about CFWN but I was really surprised to see that the CFW 10X pair I bought do show a (faint but clearly visible) orangeish halo at the image circle limit. The orangeish halo is typical of compensating eyepieces and the CF system is supposed to do not need compensation. I only have one finite CF objective, a M Plan Apo 40/0.80 and it shows some lateral CA. I haven't yet tested them together as I don't have a 210 microscope but I plan to do it with a spacer in my 160 microscope.

My (very provisional and not well supported) conclusion is that the CF system is not so fully "color free" as advertised, could the CFN be?
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JohnyM



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PostPosted: Mon Jun 25, 2018 2:50 pm    Post subject: Reply with quote

Interesting find. Ineed i've noticed many compensating eyepieces have orange or blue halo visible.
I also found my CFN apo's show lateral ca... example:
http://www.photomacrography.net/forum/viewtopic.php?p=220580&sid=77216b3838dfcf6e6cbef63471ae1df2

Seems fluor are free of it and lo ca is eazily corrected!
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Ichthyophthirius



Joined: 07 Mar 2013
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PostPosted: Sun Jul 01, 2018 9:08 am    Post subject: Reply with quote

Hi,

CFW are the first generation of CF eyepieces (go with CF objectives), CFWN is a later generation (at the same time as the CFN objectives).

"N" probably just means "new"?? www.krebsmicro.com/Nikon_CF.pdf The CFN generation of objectives had slightly higher NA than the previous generation.

For the small 23.2 mm eyepieces, the difference is the field number. CFW are 10x/18 and CFWN are 10x/20. The CFUW and CFUWN eyepieces are both 10x/26.5.

CF and CFN series both have the same kind of "colour free" design as far as I know. There is a tiny bit of CDM left (see page 5, red lines: www.alanwood.net/downloads/olympus-lb-objectives.pdf ) but that doesn't matter in practice.

Regards, Ichty
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JohnyM



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PostPosted: Sun Jul 01, 2018 1:07 pm    Post subject: Reply with quote

What "CDM" stands for?
I have seen both CFUWN and CFUW 10x/25. I also have CFUWN 10x/26.5 but they are stared to work with metallurgical CF objectives only and i've never seen CFUW with FN higher than 25.


Last edited by JohnyM on Mon Jul 02, 2018 1:02 am; edited 1 time in total
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Pau
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PostPosted: Sun Jul 01, 2018 2:35 pm    Post subject: Reply with quote

JohnyM wrote:
What "CDM" stands for?

"chromatic difference in magnification" (radial CA)

http://www.photomacrography.net/forum/viewtopic.php?p=160172#160172
http://www.microscopy-uk.org.uk/mag/indexmag.html?http://www.microscopy-uk.org.uk/mag/artfeb02/tccdm.html
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abednego1995



Joined: 01 Nov 2016
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PostPosted: Sun Jul 01, 2018 8:51 pm    Post subject: Reply with quote

Regarding only the 10x oculars, obviously because including the 8x, 12.5x, 15x is a bit confusing...

At the introduction of CF objectives in 1976, Nikon offered CFW(FN18mm. old style, like the HKW from the S series) and CFUW(FN26.5. again old style plus diopter adjustment) for the new Biophot.
In 1978 the Optiphot and Labophot are introduced and they begin to offer the yellow marked CFW(FN18mm,rubber eyecups).In 1981 they introduce an ocular called the CFD(FN18) which touts
better correction at the outermost field periphery.

The CF system albeit having "most" of the CDM corrected, still has slight amount of CDM left at the field extremes. In the original CFW eyepiece, they compensate for a sweet spot at around FN16mm.
So through the CFW slight fringing (barely apparent) is left at the periphery. The CFD corrects for the full field of FN18, albeit for a higher(much much higher, actually more than the CFUW...) price.
This CFD was a shortlived ocular, already removed from lists by 1985.

In 1985, the NCF(or CFN: this actually is a wrong designation.) objectives come out and the CFW was updated to the CFDW(FN18, the lens label still says CFW in yellow).
So, there are 2 distinct but indistinguishable generations in CFW oculars! In 1990, the Optiphot/Labophot-2 is introduced, and the oculars are updated to CFWN(FN20mm), CFUWN(FN26.5mm).

So... in short, there is an overlapping period from CF to NCF and CFW to CFWN, and that indicates that CF, NCF objectives and oculars are compatible with each other, with nearly the same amount of CFD
though with slight differences in cosmetics, lens design.
(I personally avoid the CFWN oculars since they tend to lose transparency at the cemented doublet, leaking grease, and extremely weak plastic prong inside that limits the diopter adjustment)

As for the oculars with FN22mm, and FN25mm, they are for the CFI series of objectives and are a different story. (Usable, sure. But not sure if they were meant to be used with legacy systems.)
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JohnyM



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PostPosted: Mon Jul 02, 2018 1:20 am    Post subject: Reply with quote

So "CDM" is just a fancy name for longitudinal chromatic abberation.


abednego1995 wrote:
Regarding only the 10x oculars, obviously because including the 8x, 12.5x, 15x is a bit confusing...

I personally cant see any use for eyepieces that gives less FOV and nothing else (having optovar helps).

abednego1995 wrote:
In 1981 they introduce an ocular called the CFD(FN18) which touts
better correction at the outermost field periphery... ...In 1985, the NCF(or CFN: this actually is a wrong designation.) objectives come out and the CFW was updated to the CFDW(FN18, the lens label still says CFW in yellow).
So, there are 2 distinct but indistinguishable generations in CFW oculars!

That's all very interesting. Can you point to any source? Google isnt finding anything.

Quote:
In 1990, the Optiphot/Labophot-2 is introduced, and the oculars are updated to CFWN(FN20mm), CFUWN(FN26.5mm).


Why everyone insist on 26.5 here? BIO CFUWN's are 25.
26.5 were made much later for newer generations of EPI Optiphots with infinite objectives.

Quote:
(I personally avoid the CFWN oculars since they tend to lose transparency at the cemented doublet, leaking grease, and extremely weak plastic prong inside that limits the diopter adjustment)

All my CFWN eyepeces are still in pristine oprical condition (education purposed labophots - still work great), but about half of them have diopter regulation broken indeed.
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abednego1995



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PostPosted: Mon Jul 02, 2018 2:29 am    Post subject: Reply with quote

Yup. As far as I understand, CDM and LoCA is the same thing.
JohnyM wrote:
So "CDM" is just a fancy name for longitudinal chromatic abberation.


Please see the attached snippets. Some are in Japanese, but I'm sure you can make out the crucial numbers.
JohnyM wrote:

abednego1995 wrote:
In 1981 they introduce an ocular called the CFD(FN18) which touts
better correction at the outermost field periphery... ...In 1985, the NCF(or CFN: this actually is a wrong designation.) objectives come out and the CFW was updated to the CFDW(FN18, the lens label still says CFW in yellow).
So, there are 2 distinct but indistinguishable generations in CFW oculars!

That's all very interesting. Can you point to any source? Google isnt finding anything.


1st, initial CF lens lineup for Biophot, 1976. Oculars are on the lower left of the scan.


2nd, new product leaflet for 1981. The CFD 10x debuts!


3rd, CF objective price list from 1985(Just at/before the transition to NCF).


4th, NCF (not CFN) objective list from 1994. (and yes, I've seen the objective catalog from Charles Krebs site, and it states them as "CF N". However catalogs within Japan don't follow this..curious.)
Oculars are on the lower 2nd table. They state CFUWNs as FN26.5.



Counter intuitive, but Nikon actually reduced the FN of the newer oculars(CFIUW) since many users didn't require that much field.
JohnyM wrote:

Quote:
In 1990, the Optiphot/Labophot-2 is introduced, and the oculars are updated to CFWN(FN20mm), CFUWN(FN26.5mm).


Why everyone insist on 26.5 here? BIO CFUWN's are 25.
26.5 were made much later for newer generations of EPI Optiphots with infinite objectives.
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Pau
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PostPosted: Mon Jul 02, 2018 2:38 am    Post subject: Reply with quote

abednego1995 wrote:
Yup. As far as I understand, CDM and LoCA is the same thing.
JohnyM wrote:
So "CDM" is just a fancy name for longitudinal chromatic abberation.


Not longitudinal, it refers to radial = lateral CA
LoCA is due to different focus distance of the different wavelengths while CDM is due to different magnification (ie different angle) of them
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abednego1995



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PostPosted: Mon Jul 02, 2018 3:09 am    Post subject: Reply with quote

Bummer me, thanks Pau. I'm still learning! :-)
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Pau
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PostPosted: Mon Jul 02, 2018 3:53 am    Post subject: Reply with quote

abednego1995 wrote:
I'm still learning! :-)


Me too...if not it would be a bad thing Very Happy
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JohnyM



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PostPosted: Mon Jul 02, 2018 5:07 am    Post subject: Reply with quote

Of course lateral. I have troubles in naming them with english. Thanks for pointing it out.

Very interesting snippets. Thanks for sharing them.

Maybe you have something about N CF / CF N plan fluors?
I have whole set, but never seen them in any brochure. Also got De'Senarmont DIC sliders for them, which arent mentioned in DIC brochures i've seen.

Interesting info about that 26,5 FN. I distinctivly remember reading that they are meant for metallurgical microscopes only and will vignette on biological microscopes. I'll try to search for it.
Also:
On Microphot SA 26,5 is hardcore vignetting while 25 is not. I dont have other UW heads on old nikons to check.

Edit: so far found this in Optiphot 2 manual
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Ichthyophthirius



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PostPosted: Mon Jul 02, 2018 6:51 am    Post subject: Reply with quote

abednego1995 wrote:

Please see the attached snippets. Some are in Japanese, but I'm sure you can make out the crucial numbers.


Hi,

Thanks for all the documentation! I've never noticed the "CFD" designation before.

Since you're here: Do you have any information on the CF Plan Fluor objectives (biological objectives, e.g. Plan Fluor 20/0.50 160/0.17)? They must have been introduced very late, just before the switch to CFI, and I've never seen documention about them, e.g. working distances.

Regards, Ichty
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JohnyM



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PostPosted: Mon Jul 02, 2018 7:03 am    Post subject: Reply with quote

Working distances seems to be identical with plans.
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